Electrical products of today are required to provide acceptable protection for users and other people who are handling the electrical device or simply who are at risk for being exposed to electrically conducting parts which accidentally may be live. A common way of protecting people from getting hurt in this situations is to have the electrically conducting part connected to ground. Thereby a circuit breaker, a residual-current Device (RCD), or a Ground Fault Circuit Interrupter (GFCI) will be able to switch off the electric circuit, because of the ground connection, when the electrical conducting part becomes live. Another way to protect people from parts of device that may be electrified is to provide sufficient electrical isolation between electrically live parts and parts that people may touch when the device is in use. Many electrical devices are provided with protective ground via the mains power supply. However in networked devices the trend is to power the networked device using Power Over Ethernet (POE) and in order to provide protective earth the network cable must provide the protective earth. This is usually provided in the shield.
Accordingly, if the user connect a networked electrical device using a cable without protective earth then no protective earth is provided. If the electric device is to be protected against electrical surges, the device may be equipped with an electric surge protecting device too. However, such a device require a ground connection and in many cases devices including electric surge protecting devices are provided with a separate ground cable. A device that is equipped with protective earth via a separate ground cable may be considered safe even if the electric device is connected to the network using a non-shielded network cable, thereby lacking the ground connection via the network cable. Some networked devices, e.g. monitoring cameras may be installed outdoors as well as indoors. If the device is installed outdoors the camera is recommended to be connected to a separate ground cable via a surge protector and a ground terminal connected to the housing of the electrical device. The surge protector is mainly included to protect the device against current surges, e.g. from lightning strikes, and is relying on sufficient electrical grounding of the surge protector.
Regarding the personal protection aspect, many electrical devices have metal housing which easily may become hazardous for a person handling the electric device. However if the device is connected to a separate ground cable it does not matter if the network cable have a ground connection as the electrical device and its housing is connected to ground via the separate ground cable.
If the networked electronic device is installed indoors, the separate ground cable is not usually corrected to the ground terminal and the housing of the electrical device as there are less risk for the need of the services of a surge protector. This is not a problem as long as the network cable includes a wire connected to ground and to the housing of the device. However, if a network cable with no protective earth is connected to the device and the ground connections of the networked electric device still is connected to the electrically conducting housing via the ground terminal, then the electronics of the electric device is directly connected to the housing which is without any connection to protective earth. This is potentially a dangerous situation for users handling the electronic device. The situation may be solved by isolating the ground connections in the electronic device from the housing. However, then the person installing the device or another person operating the device has to make sure that every time a ground cable for surge protection is connected to the electronic device an electrical insulation arranged between the electronics of the electric device and the ground terminal is removed. Alternatively, if there is no ground connected to the housing such electrical insulation has to be inserted between the electronics of the electric device and the housing of the electric device. Another option is to say that the device only is allowed to be used with a network cable having a protective earth line.
Anyhow, the problem is that there are too many risk scenarios leading to the electric device becoming an electrical hazard to a person handling it. Even if you require that a safety protocol is followed the situation will not be risk free. For instance, ponder the situation where a ground cable is not connected and the installer forgets to isolate the interior to the housing. Then the electrical safety relies on the network cable having the protective earth, but even if the person installing the device followed the protocol and used a grounded network cable, someone may exchange the original cable to a cable without a protective earth at any time. Accordingly reliable electrical safety for users are a problem.